This invention relates, in general, to turbomachinery; and, in particular, this invention relates to a stationary to stationary seal between adjacent turbomachine sections.
A large turbomachine may comprise several axially aligned sections including a dynamoelectric machine or generator all connected in tandem by a common rotor shaft. Each section includes a rotor portion which is supported by a pair of bearings, one at each end of each stage. The rotor portions are coupled to adjacent rotor portions to form the single common rotor. Each bearing is supplied with high pressure oil for lubrication and cooling after which the oil is drained from the turbomachine section. In order to prevent oil from leaking out of the turbomachine stage and also to prevent air and dirt from entering the oil supply, it is customary to provide shaft seals for the rotor. A shaft seal is an annulus which extends radially inwardly from the hood or casing and terminates in a clearance fit closely adjacent the rotor. The free end of the annulus is provided with packing teeth and the clearance may be on the order of a few mils.
Occasionally a packing rub may occur whereby the rotor contacts the surrounding packing teeth or shaft seal. Such an occurrence may cause damage to the rotor and/or damage to the packing teeth and shaft seal. If the effectiveness of the shaft seal is diminished, oil may leak from the turbomachine. Another consequence of diminished seal effectiveness is the ingress of air and dirt into the turbomachine oil supply. If air enters the oil supply frothing may occur. If dirt or lint enters the oil supply a bearing may be damaged, and/or valve clogging and oil passage clogging may result.
Another factor in the design of shaft seals is the relative movement of turbomachine casings or hoods due to thermal differences.
It is therefore one object of the present invention to provide a turbomachine seal which is not subject to rotor contact or packing rub.
It is another object of the present invention to provide a turbomachine seal which may accommodate relative thermal movement of adjacent turbomachine sections.
A further object of the present invention is to provide an improved turbomachine seal which may be easily assembled between adjacent turbomachine sections.
Still another object of the present invention is to provide an improved turbomachine oil seal which is based on an interference fit between sealing elements rather than a clearance fit.
Another object of the present invention is to provide a stationary to stationary oil seal rather than a stationary to rotating oil seal hereinafter described.
The present invention relates to an oil seal positioned between adjacent turbomachine sections. An annular, axially extending wrapper is attached to one adjacent turbomachine section hood. The wrapper surrounds the turbomachine rotor but is spaced radially outwardly therefrom so as to obviate the occurrence of a shaft rub. An annular first sealing element is attached to another adjacent turbomachine section hood and extends radially inwardly towards the turbomachine rotor terminating at the wrapper outer surface in an interference fit. Moreover, appropriate oil deflectors are provided axially adjacent the ends of the wrapper with the wrapper included therebetween.
The novel features believed characteristic of the present invention are set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof, may best be understood with reference to the following description, taken in connection with the appended drawings.